Fintech welcome emails: auditing bounce handling without SMTP

The article argues that welcome emails should be sent once, with delivery events polled outside the signup request and every permanent bounce or complaint converted into a suppression decision before further sends are queued. It recommends keeping the event, the decision, and the message correlation ID as separate audit evidence, since a simple 'bounced' status is weak proof on its own. The proposed design uses four durable records: recipient state, outbound intent, raw provider event, and suppression decision, with an internal communication ID as the primary join key. Each imported event is logged with its ID, timestamps, and a payload digest, while sensitive onboarding data is kept out of the logs. The author also stresses that acceptance, delivery, inbox placement, and reading are distinct claims that should not be merged into a single 'sent' flag.